Development of C-Shaped Parasitic MIMO Antennas for Mutual Coupling Reduction

Abstract

In the 5G system, multiple-input multiple-output (MIMO) antennas for both transmitting and receiving ends are required. However, the design of MIMO antennas at the 5G upper band is challenging due to the mutual coupling issues. Many techniques have been proposed to improve antenna isolation; however, some of the designs have impacts on the antenna performance, especially on the gain and bandwidth reduction, or an increase in the overall size. Thus, a design with a detailed trade-off study must be implemented. This article proposes a new C-shaped parasitic structure around a main circular radiating patch of a MIMO antenna at 16 GHz with enhanced isolation features. The proposed antenna comprises two elements with a separation of 0.32λ edge to edge between radiation parts placed in a linear configuration with an overall dimension of 15 mm × 26 mm. The C-shaped parasitic element was introduced around the main radiating antenna for better isolation. Based on the measurement results, the proposed structure significantly improved the isolation from −23.86 dB to −32.32 dB and increased the bandwidth from 1150 MHz to 1400 MHz. For validation, the envelope correlation coefficient (ECC) and the diversity gain (DG) were also measuredas 0.148 dB and 9.89 dB, respectively. Other parameters, such as the radiation pattern, the total average reflection coefficient and the mean effective gain, were also calculated to ensure the validity of the proposed structure. Based on the design work and analysis, the proposed structure was proven to improve the antenna isolation and increase the bandwidth, while maintaining the small overall dimension.

A review on techniques for improving mimo antenna performance in smart 5g devices

“…The 2 circular radiating elements of the MIMO antenna array [34] reported with the edge to edge spacing of 0.32 lambda is introduced with the C-shaped structure encompassing the circular radiator for reducing isolation. A 6 port MIMO antenna is designed to support multiple bands of resonance i.e.…”

A Compact Two-Element Linearly and Orthogonal Circularly Polarized MIMO Antenna System for 5G Cellular and WLAN/Wi-Fi 6E Application

“…Although these decoupling structures have improved the isolation between MIMO elements, most of these solutions are complicated or introduce extra space for the design [17]. It can be achieved using C-shaped parasitic decoupling structures [18]. Employing neutralized line (NL), techniques construct an antiphase current route to the coupling between array elements [19].…”

Self-Interference Cancellation: A Comprehensive Review from Circuits and Fields Perspectives

“…Another way is to use a circulator to share one antenna for both transmitting and receiving [17,18]. Isolators, such as the parasitic elements, metamaterial inspired isolators, and electromagnetic bandgap structures, have also been studied in previous research [19][20][21][22]. These passive approaches can be easily realized, but the isolation performance is normally limited, especially when the interference channel varies in time.…”